This invention relates to needle safety devices for medication delivery pens, and more particularly, to manually-actuated safety devices for medication delivery pens.
Medication delivery pens are known in the art and are used extensively for self-administered injections, particularly with insulin. Although a medication delivery pen is normally only handled by its user, concerns exist with inadvertent skin penetration by a used pen injection needle (also referred to as a “needle stick”) particularly after disposal of a used needle.
Devices have been developed in the prior art for shielding a used medication delivery pen needle. Generally, prior art devices require complex parts and/or a multiplicity of parts. As a result, these prior art devices may not only be expensive, but may also be susceptible to failure due to their complexity. For example, U.S. Pat. No. 5,964,731, which issued on Oct. 12, 1999, discloses a manually-actuatable needle cover which includes a needle cover that is rotated through a helical track into a locked shielding position. This device, however, requires both the shielding element and an outer collar which includes the helical track. In an alternative design, as disclosed in U.S. Published patent application Ser. No. US 2002/0133122 A1, which published on Sep. 19, 2002, a normally-biased-closed shield is disclosed which is retracted upon pressing engagement against the skin of a patient. After administration, the shield locks in a protective position about the used needle. Although this device provides passive shielding without patient involvement, patients have no or poor visual contact of the needle cannula end to observe priming of the needle before use (priming of the needle is typically recommended with a small amount of liquid being expelled from the needle prior to injection to ensure that no air bubbles are entrapped within the needle).